import numpy as np
import cv2 as cv


def main():
    img = np.ones((512, 512, 3), np.uint8) * 255

    start_point = (20, 20)
    end_point = (round(img.shape[1] / 2), round(img.shape[0] / 4))
    color = (0, 255, 0)
    thickness = 3

    cv.rectangle(img, start_point, end_point, color, thickness)
    cv.imshow("Press any key to exit", img)
    cv.waitKey(0)
    cv.destroyAllWindows()


if __name__ == "__main__":
    main()